Method of coating an elongated body

ABSTRACT

A CONTINUOUS METHOD OF COATING A CLEAN STEEL WIRE OR THE LIKE WITH RESIN INCLUDES APPLYING PRIMER TO THE WIRE, DRYING THE PRIMER COATING BEFORE HEATING IT AND PREHEATING THE PRIMED OBJECT BY PASSING IT THROUGH AN INDUCTION COIL WITH THE PRIMER COATING THEREON AND AT THE SAME TIME APPLYING A COOLING GAS THERETO TO PURGE PRIMING FUMES AND TO KEEP THE INDUCTION COIL FREE OF ACCUMULATIONS. THE HEATED WIRE IS THEN PASSED HORIZONTALLY THROUGH A FLUIDIZED BED OF POWDERED RESIN AFTER WHICH THE COATING IS FUSED ON THE WIRE.   D R A W I N G

W. K. FACER ETAL METHOD OF COATING AN ELONGATED BODY Original Filed March 25, 1964 OOOOOOOOOOOO I !!!lfllllfllllflA/l/llllldIf/lllff/IV/Yfflf/llffdl/f/l/llI/l/Jff Feb. 2, 1971' 0W4 m M .I P Mm k 4 .m fi m l INVENTORS WALTER K. FACE/i and JANE H. M. R/GO By Alla/nay United States Patent 3,560,239 METHOD OF COATING AN ELONGATED BODY Walter K. Facer, Parma, Ohio, and Jane H. M. Rigo, Monroeville Borough, Pa., assignors to United States Steel Corporation, a corporation of Delaware Original application Mar. 25, 1964, Ser. No. 354,594, now Patent No. 3,476,081. Divided and this application July 10, 1969, Ser. No. 840,750

Int. Cl. B44d 1/095, 1/42 US. Cl. 11717 Claims ABSTRACT OF THE DISCLOSURE A continuous method of coating a clean steel wire or the like with resin includes applying a primer to the wire, drying the primer coating before heating it and preheating the primed object by passing it through an induction coil with the primer coating thereon and at the same time applying a cooling gas thereto to purge priming fumes and to keep the induction coil free of accumulations. The heated wire is then passed horizontally through a fluidized bed of powdered resin after which the coating is fused on the wire.

This application, which is a division of our co-pending application Ser. No. 354,594, filed Mar. 25, 1964, now Pat. No. 3,476,081 relates to a method of coating an elongated body and more particularly to the coating of a steel wire with resin. This type of coating has been applied by various methods, but those of which we have knowledge have various disadvantages. For example, it is difllcult to coat various size wires readily and/or to obtain the desired coating thickness. Difficulty is also encountered in obtaining a suitable primer on the wire before coating.

It is therefore an object of our invention to provide a method of coating an elongated object with resin wherein different size objects can be provided with suitable coatings of various thicknesses.

Another object is to provide such a method wherein a primer is applied uniformly to the object.

These and other objects will be more apparent after referring to the following specification and attached drawings in which:

FIG. 1 is a schematic view of a coating line suitable for practicing our invention;

FIG. 2 is a view, partly in section, of the priming unit used in our invention;

FIG. 3 is a view, partly in section, of the coating unit used in our invention; and

FIG. 4 is a sectional view of a detail of the coating unit.

Referring more particularly to the drawings, reference numeral 2 indicates a pay off reel for supporting a coil of wire W to be coated. The wire W passes through standard roll straighteners 3 to a cleaning tank 4 of any suitable type and then through a water rinse tank 6. From here the wire W passes successively through a priming unit 8, drying unit 10, preheat induction coil 12, coating chamber 14 post heat induction coil 16, fusion area 18 and water quench 20 to a take up 22 where it is coiled. While the description will be directed to the coating of wire; strand, cord, rope, strip or like elongated structures may be coated as well with only slight modification.

The priming unit 8, as shown in FIG. 2 includes a chamber 24 having a spiraled cord wipe 26 therein through which the wire W passes. A liquid primer is delivered into chamber 24 and directed onto wire W through a conduit 28 and is returned to a reservoir (not shown) through a drain 30. The coating chamber 14 as shown in FIGS. 3 and 4 has end walls 32 and 34 with aligned openings 36 and 38 therein. An entry air seal 40 is supported on the Wall 32 and an exit air seal 42 is supported on the wall 34. The seal 40 includes a hollow cylindrical member 44 having an externally threaded reduced diameter portion 46 and a larger diameter portion 48. The portion 46 has an axial opening 50 therethrough which is only slightly larger than the diameter of the wire W. The portion 48 has an opening or chamber 52 therein which is connected to the opening 50 by means of a beveled portion 54 which is preferably arranged at an angle of to the axis of the wire. Threads 56 are provided on the inlet side of opening 52 and a nozzle 58 is threaded into the threads 56. The forward end of nozzle 58 is tapered at the same angle as tapered portion 54. The air seal 40 is attached to the wall 32 by means of a nut 60 threaded on portion 46. A gasket or other sealing member 62 is provided between the portion 48 and the outside of wall 32. The nozzle 58 is threaded into threads 56 an amount such that a conical port 64 is provided for air passage. The size of the opening of port 64 may be varied as desired. A lock nut 66 threaded on the outside of nozzle 58 and bearing against member 44 holds the nozzle in adjusted position. Air is delivered into the chamber 52 through a conduit 68. The air seal 42 has essentially the same construction as air seal 40 and corresponding parts are indicated by priming the reference numerals applied to the parts of air seal 40. The openings through portion 46 and nozzle 58' are substantially larger than the openings through portion 46 and nozzle 58. Air is delivered into chamber 52' at diametrically opposed positions through conduits 70 and 72.

An air diffusion board 74 is arranged a short distance above bottom 76 of the chamber 14. A manifold 78 supported on top of chamber 14 has a chamber 80 around its periphery. Inner walls 82 of the manifold 78 have closely spaced holes 84 therein for a purpose which will appear later. A conduit 86 is connected to the manifold 78 and leads to a suction fan 88. A deflector plate 90 is mounted on each end wall above the air seal and extends downwardly and inwardly. Preferably the plates terminate a short distance from each side of chamber 14. Two vertical partitions 92 are arranged in the chamber 14 intermediate the ends thereof. Each partition 92 in cludes flanged members 94 around the transverse periphery of chamber 14. The bottom member 94 preferably has a downwardly extending flange 95 which divides board 74 into sections. A plate 96 is attached to the member 94 with a sealing member 98 therebetween. Each plate 96 has an opening 100 therethrough which is an alignment with openings 36 and 38. Dividers 102 are provided in plenum chamber 104 formed between the bottom 76 and diffusion board 74. A seal 103 is provided between the top flange of divider 102 and the bottom of boards 74.

Air is delivered into the chamber 104 from an air source (not shown) through air manifold 106 and branch conduits 108, 110 and 112. The conduits 108, 110 and 112 have valves 114, 116 and 118 therein. A removable cover 120 is preferably provided over at least a portion of the top of the manifold 78. Air is delivered along the wire W into the induction coil 12 through an air conduit 122. Valves 124, 126, 128 and 130 control the flow of air through conduits 68, 70 and 72 into the air seals and through the conduit 122.

In operation, wire W is threaded through the line and a granulated resin material 132 is placed in the coating chamber 14. This resin may be thermoplastic or thermosetting. The type of resin does not form any part of the present invention but the following resins have been used: Cellulosic, chlorinated polyether, epoxy, nylon, polyester, polyethylene, dry blended vinyl and prefused freeze-ground vinyl. Assuming that the wire is of small diameter and that a thick coating is to be applied, the exit seal 42 will be attached to the end wall 34 as shown. The line is then started in operation with the valves 114, 116 and 118 being open. As the straightened clean Wire passes into chamber 24 liquid primer is directed directly onto the wire W and after partial draining the primer is more uniformly distributed by passage through the wool felt cord 26. At a given speed, primer feed, and wire diameter, the thickness of the primer may be varied by changing the number of wraps of the cord 26 around the wire. The primer materials form no part of the present invention but that sold by Michigan Chrome and Chemical Company as MC1445 primer and that sold by Polymer Processes Incorporated as VC primer have been used. The primer is then dried in the drying unit and the Wire W preheated as it passes through induction coil 12. Flow of air through conduit 122 into the coil 12 has been found necessary in order to purge the priming fumes and to keep the coil free of accumulations. Most of the fumes will be driven back into drying chamber 10 by this air. As the wire W passes through the fluidized bed of powdered resin 132 it picks up a coating of the same. The bed is kept in a fluidized state by means of the air passing through the diffusion board 74 and also by the air passing through the air seals. The deflectors 90 prevent this latter air from rising directly through the bed at each end. Air movement at the end seals prevents dead space in or around the seal so as to prevent agglommeration of the resin at the wire entrance and exit points. The air at the exit seal blows excess powder from the wire and prevents escape of powder from the tank. The wire from the coating chamber 14 passes through the fusion zone 18 where the particles of resin on the wire fuse together and to the wire to obtain a smooth surface. In some instances heat will be supplied to the wire W by means of the induction coil 16. This is done only when additional heat is required on the wire which is most likely to occur with small diameter wires. The fused wire then passes through the water quench 20 and hence to the take up 22 where it is coiled.

When coating wires of larger diameter it has been found that the length of the fluidized bed should be reduced. This is also true when a thin resin coating is desired or when the wire is passed through the line at slow speeds. When this is done the exit seal 42 and deflector 90 are attached to one of the partitions 92 and the powdered resin is placed only in the space between the seals. Assuming that the seal 42 and deflector 90 are placed on the first of the partitions 92, as shown in broken lines in FIG. 3, valves 116 and 118 are closed and valve 114 opened. Also the openings 84 between the first partition 92 and the end wall 34 are closed in any suitable manner. This may be done by merely placing adhesive tape thereover. The flange 95, divider 102 and seal 103 restrict air flow from chamber 104 to the fluidized bed in the first compartment of chamber 14. Fumes and air passing through the openings 84 are drawn through conduit 86 by means of suction fan 88.

While one embodiment of our invention has been shown and described, it will be apparent that other adaptations and modifications may be made.

We claim:

1. The method of continuously coating a clean elongated object with resin which comprises applying a liquid primer to said object, drying the primer coating, preheating the primed object by passing it through an induction coil with the primer thereon and at the same time applying a cooling gas thereto to purge priming fumes and to keep the induction coil free of accumulations, then passing the heated and primed object horizontally through a fluidized bed of heat fusible powdered resin in a chamber, and maintaining the fluidized bed by passing a gas upwardly therethrough and preventing escape of the powdered resin by delivering gas inwardly into said chamber around said object as it passes through openings in the end walls of said chamber.

2. The method of continuously coating an elongated object with resin according to claim 1 which includes fusing said coating on said object after it leaves said chamher.

3. The method of continuously coating an elongated object with resin according to claim 2 which includes removing gas from said chamber through openings in the wall thereof adjacent the top thereof, and varying the length of the fluidized bed depending upon the size of the object being coated and the thickness of coating desired.

4. The method of continuously coating an elongated object with resin according to claim 1 which includes regulating the flow of gas at the exit opening to remove excess resin therefrom, directing the gas entering through said end openings downwardly to assist in the fluidizing, removing gas from said chamber through openings in the wall thereof below the top thereof, and varying the length of the fluidized bed depending upon the size of the object being coated and the thickness of coating desired.

5. The method of continuously coating an elongated object with resin according to claim 1 which includes removing gas from said chamber through openings in the wall thereof adjacent the top thereof, and varying the length of the fluidized bed depending upon the size of the object being coated and the thickness of coating desired.

References Cited UNITED STATES PATENTS 3,008,848 11/1961 Annonio 117-72 3,108,022 10/1963 Church 117-21 3,140,195 7/1964 Nagel 117-29 3,161,530 12/1964 Strobel 117-18 3,208,868 9/1965 Strobel et a1. 117-18 3,208,869 9/1965 Starr et al. 117-18 3,233,584 2/ 1966 Angstadt 117-21 3,303,041 2/1967 Thompson 117-18 3,436,244 4/ 1969 Yokawonis 117-18 OTHER REFERENCES Gemmer, translation of Das Wirbelsinter-Verfahren -Grundlagen, Verfahren und Ger'alte in Plastverarbeiter, September 1956, page 16.

WILLIAM D. MARTIN, Primary Examiner R. M. Speer, Assistant Examiner US. Cl. X.R. 

